Biodegradable plastics are widely used in consumer products from packing materials to grocery bags. A key component of these materials is their ability to degrade as well as the byproducts of the degradation be biocompatible and environmentally friendly. The polymer compositions reported herein degrade to CO2 and glycerol.
Li-ion batteries are widely used for portable devices in the current electric market due to their high gravimetric and volumetric energy densities and cyclability (Xu, K. Nonaqueous Liquid Electrolytes for Lithium-Based Rechargeable Batteries. Chem. Rev. 2004, 104, 4303-4417. Quartarone, E.; Mustarelli, P. Electrolytes for solid-state lithium rechargeable batteries: recent advances and perspectives. Chem. Soc. Rev. 2011, 40, 2525-2540). Recent developments in Li-ion battery technology have increased their performance and decreased their costs, which have led to their widespread use in everything from cell phones to electric vehicles. However, performance and safety issues still remain a concern. These concerns include capacity loss with cycling and thermal stability when operating above room temperature (Aurbach, D.; Talyosef, Y.; Markovsky, B.; Markevich, E.; Zinigrad, E.; Asraf, L.; Gnanaraj, J. S.; Kim, H.-J. Design of electrolyte solutions for Li and Li-ion batteries: a review. Electrochimica Acta 2004, 50, 247. Goodenough, J. B.; Kim, Y. Challenges for Rechargeable Li Batteries. Chem. Mater. 2010, 22, 587-603). Overcharging and extreme discharging of Li-ion batteries can lead to overheating and thermal runaway; while improper use of a Li-ion battery can lead to fire or explosion. 8 The volatility and flammability of the organic solvents (EC/DMC) used in typical Li-ion electrolytes are the major source of these thermal stability issues. Consequently, replacement of conventional electrolyte solutions with a non-flammable, non-volatile material to create a Li-ion battery for operation at room temperature and above is highly desirable and would represent both a basic and technological advancement.
Medicine traditionally utilizes pharmacologic agents or surgical interventions for the treatment of disease. Specific targeting or localization of pharmacologic or biologic agents to desired organs and tissues is a complex challenge.
For example, delivery of agents to tumors to treat or cure cancer is limited by non-specific targeting, agent degradation, and high systemic toxicity, to name a few. Treatments of conditions such as cancer remain relatively ineffective as evidenced by high rates of cancer recurrence and low survival; cancer is a leading cause of death for both men and women in the United States (Jemal et al., CA Cancer J. Clin., 60:277-300, 2010). Current methods of cancer treatment include chemotherapy, radiation treatment, and surgical resection.
Other medical applications which utilize drug delivery technologies include immunological applications, pain control, wound healing, infectious disease, transplants, and the development of vaccines. Potential drug candidates often present solubility, toxicity, and/or pharmacokinetic concerns. Thus, there is a broad need for locally and regionally targeted and sustained delivery of therapeutic agents.
Certain polyesters, polycarbonates, and polyamides are biodegradable polymers with low toxicity and degradation properties. Such polymers include poly(ε-caprolactone), poly(p-dioxanone), poly(trimethylene carbonate), and most notably poly(glycolic acid) and poly(lactic acid)(see, e.g., Agrawal et al., Biomaterials, 13:176-182, 1992; Attawia et al., J. Biomed. Mater. Res., 29:1233-140, 1995; Heller et al., Adv. Drug Deliv. Rev., 54:1015-1039, 2002; Miller and Williams, Biomaterials, 8:129-137, 1987; and Athanasiou et al., Arthroscopy, 14:726-737, 1998). These polymers are used in a variety of applications including the delivery of therapeutic agents. However, physical properties of the aforementioned polymers are limited by monomer selection, polymerization techniques and post-polymerization modifications. Properties of interest include thermal transition temperatures, bulk strength, flexibility or elasticity, degradation, crystallinity, and hydrophobicity. When polymers are utilized for in vivo applications, the physical properties of the material affect host response. Hence, a need exists for polymers and delivery systems with desired characteristics that are effective for treatment of diseases and conditions in vivo and that can be tailored for specific therapeutic needs and tissue characteristics.
Linear poly(1,3 glycerol carbonate)s are known and synthesized via ring-opening polymerization of the six-membered 3-benzyloxytrimethylene carbonate (Ray, W. C.; Grinstaff, M. W. Macromolecules 2003, 36, 3557-3562, He, F.; Wang, Y.; Feng, J.; Zhuo, R.; Wang, X. Polymer 2003, 44, 3215-3219. (27) Helou, M.; Miserque, O.; Brusson, J. M.; Carpentier, J. F.; Guillaume, S. M. Chemistry—A European Journal 2010, 16, 13805-13813) or dimethylacetal dihydroxyacetone carbonate (Zelikin, A. N.; Zawaneh, P. N.; Putnam, D. Biomacromolecules 2006, 7, 3239-3244. Zhang, X.; Mei, H.; Hu, C.; Zhong, Z.; Zhuo, R. Macromolecules 2009, 42, 1010-1016. Simon, J.; Olsson, J. V.; Kim, H.; Tenney, I. F.; Waymouth, R. M. Macromolecules 2012, 45, 9275-9281) monomers. Post polymerization, the benzyl group can be hydrogenated or the ketone can be reduced to afford a hydroxyl group, respectively. Although these routes provide ample materials, the monomers require 2-3 steps for preparation and the resulting polymers possess a secondary, less reactive hydroxyl for subsequent use and are usually of broad molecular distribution. Surprisingly, to the best of our knowledge, linear poly(1,2-glycerol carbonate)s are far less explored. These materials would likely be challenging to synthesize via the ring opening of the corresponding five-membered cyclic glycerol carbonate monomer, as five-membered cyclic carbonate monomers are thermodynamic stable and, generally, incapable of ring-opening polymerization (Rokicki, A. Prog. Polym. Sci. 2000, 25, 259-342). However these polymers may be accessed via the ring-opening copolymerization of the corresponding glycidyl ether with CO2. This polymerization route has been explored to prepare other polycarbonate polymers Coates, G. W.; Moore, D. R. Angew Chem Int Edit 2004, 43, 6618-6639. Darensbourg, D. J. Chem Rev 2007, 107, 2388-2410. Sakakura, T.; Choi, J. C.; Yasuda, H. Chem Rev 2007, 107, 2365-2387).
Poly(acrylic acid) have found extensive applications including water/sewage treatment, superabsorbent polymers, detergent, adhesives, dispersant, cosmetics, as well as drug delivery and really serve as the workhorse of chemical industry.
Despite its widespread use for both practical applications and fundamental studies, poly(acrylic acid) suffers from poor degradability which is rendered by the all-carbon backbone. It is well established that only oligomers of poly(acrylic acid)s with molecular weights (MWs) less than 600 g/mol (degree of polymerization <8) are biodegradable and yet, the molecular weights of most industrially relevant poly(acrylic acid)s are well above this value. For example, low molecular weight poly(acrylic acid)s used for detergent applications have an average MW of 4000-5000 g/mol. Furthermore, unlike structural materials (e.g. plastics) that can be easily collected and assorted for recycling or waste treatment such as land filling, composting and incineration, water soluble polymers, e.g. poly(acrylic acid)s, are difficult to recover. With all these factors coupled together, poly(acrylic acid)s constitute a major concern in industry as well as pharmaceutical and biomedical fields where biodegradability and biocompatibility are highly desired.